My law school of choice gives vague PS instructions and does not specify how long it should be. I don't need a specific word number but 1 page? 2 pages? Single spaced or double spaced?

Strictly opinion, but no more than 2 pages, single-spaced.

No less than 1 page single-spaced.

Those are broad parameters, but the main thing, I think, is that you have a tight, coherent PS that flows well, grabs attention and comes to a satisfactory conclusion at the end. Think of this in terms of writing a story. (Enlist the help of one of your fine arts friends if you need to.) Give the story an arc. Demonstrate writing skills.

That's all I can contribute from my considerably non-expert opinion. I do know that I submitted a packet and was accepted and the PS was optional. However, when I applied for a scholly, they required the PS. I ended up nabbing a half-ride, and my grades and LSAT didn't really justify that, IMHO.